Perhaps in the fanfiction, Hermione and Oliver are from different social classes in the wizarding world. The pregnancy makes them face the prejudices and expectations of their respective backgrounds. For example, Oliver might be from a pure - blood family with certain traditions, and Hermione being a Muggle - born, they have to deal with the reactions of his family. They could also have a journey where they explore different magical parenting techniques and meet other magical families who help or hinder them in their path to becoming parents.
One plot idea could be that Hermione, using her magic, ends up in the Arrowverse and meets Oliver Queen. She helps him with some of his more difficult battles using her spells and intelligence. For example, she could use a spell to disarm his enemies from a distance.
One idea could be that they discover the pregnancy during a mission. Maybe they're on a dangerous quest and Sara starts feeling unwell. It turns out she's pregnant, and they have to quickly figure out how to protect the baby while still completing their mission. Another plot could be that they initially struggle with the idea of becoming parents, given their dangerous lifestyles. They might worry about bringing a child into a world full of threats. A third idea is that their friends find out before they do, and there are some comical misunderstandings and attempts to break the news to them in a gentle way.
A really engaging plot might be that the pregnancy is the result of some sort of magical or alien influence. They initially struggle to accept it, but as time goes on, they start to embrace the new life coming. Their friends and allies might have mixed reactions, some being overjoyed while others are worried about how it will affect their superhero status. This could lead to a lot of character development and interesting relationships within the fanfiction.
One idea could be that they face challenges in their relationship while Laurel is pregnant. Maybe Oliver is worried about his vigilante life affecting their unborn child. Another could be that they discover some sort of mystery related to Laurel's pregnancy, like a new threat in the city that targets pregnant women. A third plot idea might be that they have to deal with family reactions to the pregnancy, some being happy and others being worried about their future.
A plot could revolve around Hermione's friends' reactions. For instance, Harry and Ron might be shocked at first but then become super protective. It could also show how Hermione's pregnancy affects her studies or her work in the wizarding world, perhaps she has to take a break from her research and how she copes with that.
Well, a plot could revolve around Felicity having a difficult pregnancy. Oliver then has to balance his duties as the Green Arrow and being a supportive partner. They could also have a story where they are trying to prepare for the baby's arrival while dealing with a new villain in Star City. This villain could be targeting pregnant women, making Felicity a prime target. So, Oliver has to stop the villain while also taking care of Felicity.
Maybe Oliver and Lily are in a story set in a small town. The news of Lily's pregnancy spreads quickly. They could face judgment from the community. However, they decide to use this as an opportunity to show everyone that they are mature and can handle this. They start preparing for the baby together, painting the nursery and taking parenting classes, and in the process, their relationship deepens.
One idea could be that they face challenges in their relationship due to the unexpected pregnancy. For example, Oliver might worry about how his vigilante life could affect the baby and Chloe. Another could be that they go on a journey to find a safe place for their family, away from the threats in Smallville. They could also have to deal with the reactions of their friends and family, some of whom might not be as supportive as they hoped.
One interesting fanfiction could be where Oliver discovers Hermione is pregnant and they have to navigate their relationship while dealing with the challenges of the wizarding world. For example, they might face opposition from some of their friends or family who don't think they are ready. Another could be a story that focuses on Hermione's pregnancy journey, how she copes with the physical and emotional changes while still being her intelligent, book - loving self. And there could be a fanfiction where they go into hiding during her pregnancy to protect their unborn child from some dark wizarding threat.
Perhaps there's a villain who targets Felicity because of her pregnancy. This villain could see the baby as a way to get back at Oliver. So, Oliver has to go to great lengths to keep Felicity hidden and safe. Meanwhile, Felicity could be using her intelligence to find a way to outwit the villain from her hiding place, all while dealing with the physical and emotional changes of pregnancy.